kemal-session-redis

Redis session store for kemal-session.

Installation

Add this to your application's shard.yml:

dependencies:
  kemal-session-redis:
    github: neovintage/kemal-session-redis
    version: 1.0.1

Usage

require "kemal"
require "kemal-session"
require "kemal-session-redis"

Kemal::Session.config do |config|
  config.cookie_name = "redis_test"
  config.secret = "a_secret"
  config.engine = Kemal::Session::RedisEngine.new(host: "localhost", port: 1234)
  config.timeout = Time::Span.new(1, 0, 0)
end

get "/" do
  puts "Hello World"
end

post "/sign_in" do |context|
  context.session.int("see-it-works", 1)
end

Kemal.run

The engine comes with a number of configuration options:

Option	Description
host	where your redis instance lives
port	assigned port for redis instance
unixsocket	Use a socket instead of host/port. This will override host / port settings
database	which database to use when after connecting to redis. defaults to 0
capacity	how many connections the connection pool should create. defaults to 20
timeout	how long until a connection is considered long-running. defaults to 2.0 (seconds)
pool	an instance of `ConnectionPool(Redis)`. This overrides any setting in host or unixsocket
key_prefix	when saving sessions to redis, how should the keys be namespaced. defaults to `kemal:session:`

When the Redis engine is instantiated and a connection pool isn't passed, RedisEngine will create a connection pool for you. The pool will have 20 connections and a timeout of 2 seconds. It's recommended that a connection pool be created to serve the wider application and then that passed to the RedisEngine initializer.

If no options are passed the RedisEngine will try to connect to a Redis using default settings.

Best Practices

Creating a Client

It's very easy for client code to leak Redis connections and you should pass a pool of connections that's used throughout Kemal and the session engine.

Session Administration Performance

Kemal::Session.all and Kemal::Session.each perform a bit differently under the hood. If Kemal::Session.all is used, the RedisEngine will use the SCAN command in Redis and page through all of the sessions, hydrating the Session object and returing an array of all sessions. If session storage has a large number of sessions this could have performance implications. Kemal::Session.each also uses the SCAN command in Redis but instead of creating one large array and enumerating through it, Kemal::Session.each will only hydrate and yield the keys returned from the current cursor. Once that block of sessions has been yielded, RedisEngine will retrieve the next block of sessions.